replaced dependencies (broom, dplyr, magrittr) with lighter alternatives

[mariusbarth]

Hi @hojsgaard,

thank you for this awesome package! While reading your source code, I figured that it would be quiet easy to drop some dependencies to other R packages, which will result in a more lightweight dependency graph for other R packages (especially afex).

• I replaced broom with generics, because the tidy() generic from the generics package can be safely used, and generics is much more lightweight (and also an import of broom).
• I replaced dplyr with tibble, because as_tibble() can be used from there, and tibble is more lightweight than dplyr (and also an import of dplyr).
• I removed magrittr, because it was only imported to reexport the pipe operator, but users can now use the base-R pipe.

I really hope you like these changes, because it will help me prune my dependency graphs, especially on my CI. Hope I didn't miss anything, and looking forward to your feedback!

Kind regards,
Marius

[crsh]

I'm also interested in this. These change would nicely trim the dependency tree on some of my R packages and speed up the CI pipeline for testing the packages. Cheers!